1. Field of the Invention
The present invention relates generally to fluid coupling assemblies and, more particularly, to an electrically insulated fluid coupling assembly.
2. Description of Prior Art
There are many previously known fluid coupling assemblies in which a fluid coupling has a female portion with an elongated stem that is inserted into the interior of one end of the fluid conduit. The coupling and the conduit are then secured together by a ferrule which sandwiches the end of the fluid conduit against the coupling stem.
In many applications, for example automotive applications, the fluid conduit comprises an inner layer constructed of an electrically insulating material or low level conductive material, such as a polymer, which is surrounded by a metal braid. This metal braid not only adds rigidity to the fluid coupling but also protects the fluid conduit from abrasion, impact and the like. The metal braid, in turn, is optionally enclosed in an elastomeric sheath. Such fluid couplings are used, for example, in brake lines in automotive vehicles, commercial vehicles and agricultural equipment.
One disadvantage of these previously known couplings is that the ferrule which connects the fluid coupling to the conduit is constructed of metal for high strength. This ferrule contacts not only the metal female portion of the fluid coupling, but also the metal braid. In doing so, the ferrule completes the electrical connection or circuit from the metal braid to the fluid coupling.
Consequently, in the event that a voltage is applied to the fluid coupling assembly, the ferrule completes the electrical circuit through the fluid coupling so the current flows not only through the coupling, but also through the metal braid of the conduit. In doing so, resistive heating of the fluid conduit can occur and melt or otherwise damage the inner liner of the fluid conduit. When this occurs, the overall integrity of the fluid system is compromised which can create not only system malfunction, but also a potentially hazardous safety condition. This is particularly true in fuel or other combustible liquid systems since the metal braid can become "cherry red hot."